This invention relates to hydronic heating systems which transfer a heat medium such as water to heat a radiation device to provide radiant heat. Conventionally, such radiant heat systems may be used in the home or commercially, and when used commercially, they are used to heat large areas such as floors or ceilings.
Conventional hydronic heating systems generally have a primary system in which a boiler is engaged to heat the water and a secondary system into which the water from the primary system flows under certain controlled conditions. Although the system is described with regard to a heating system, it applies equally to a cooling system, in which fluid which is cooled is carried to the radiant system in which a cooling effect is to be achieved.
Transfer of a heated or cooling fluid medium between primary and secondary systems is accomplished by means of multi-port control valves to be described hereinafter. These valves are generally motor controlled, expensive, sometimes complicated and generally undesirable as they require independently generated power, such as through a motor, to move the multi-port valve control system into various positions in order to achieve certain desired heating or cooling effects.
The following is a description of specific prior art hydronic heating systems generally employed. In this description, reference is made to FIGS. 1 through 4.
Hydronic heating systems consist of a boiler 1 used to heat a transfer medium i.e. water, a pump 2 to move the heated transfer medium from the boiler 1 to a transfer device 3 i.e. radiation to transfer the heat from the heated medium to the space to be heated, the heated transfer medium is returned to the boiler 1 at a lower temperature then it left the boiler after transferring some of its heat to the transfer device 3. See FIG. 1.
In a basic hydronic heating system, the boiler 1 heats water to the required temperature needed to be delivered to the transfer device 3 used to heat the space. This transfer device typically would be a cast iron vessel, or a copper tube with fins, that is heated by the passage of heated water through it. In certain applications it is necessary to have the temperature of the water leaving the boiler 1 to be different than the temperature of the water in the radiation system 3. In these types of applications three and four way mixing valves may be used. FIG. 2 shows the piping arrangement of a three way mixing valve.
Depending on the position of the control port in the three way valve 5, all, some, or none of the boiler water flows to the radiation system. When the control port in the three way valve is positioned so that all of the boiler water flows to the radiation system (the 100% position), the boiler port 5a is connected to the output port 5b, the radiation system 7 receives water at the boiler temperature, there is no flow in the return port 5c and all of the flow from the radiation is returned to the boiler. When the valve is in the 100% position the system functions no differently than the system shown in FIG. 1. When the valve is in a 0% boiler water position, the return port 5c is connected to the output port 5b, the radiation system 7 receives water at the returned water temperature of the radiation system, there is no flow in the boiler port 5a. In the 0% boiler position no heat from the boiler 4 is moved to the radiation system 7 and the radiation system remains at the ambient temperature. When the port of the valve is in some mid position, some percentage of the flow is through the boiler port 5a, and the remaining percentage of the flow is through the return port 5c. By blending also referred to as mixing the water leaving the boiler with water that has lost some of its heat in the radiation, a lower than boiler water temperature may be supplied to the radiation. By varying the boiler port position between 0 and 100%, the temperature supplied to the radiation system may be varied between the ambient temperature of the radiation system and the boiler water temperature. In this configuration the flow through the radiation remains constant but the flow through the boiler varies with the position of the valve. If the varying flow through the boiler presents a problem then a four way valve may be employed to maintain a constant flow through the boiler and radiation in all valve positions. The four way valve is piped into a system as shown in FIG. 3.
In a valve position of 100% boiler water, all boiler water flows into the boiler port 9a out to the radiation through the system supply port 9c, the water returns from the radiation into the system return port 9d and back to the boiler from the boiler return port 9b. In a 0% boiler water valve position, boiler water enters the boiler port 9a and returns back to the boiler through the boiler return port 9b, water in the radiation side of the valve moves out of the system supply port 9c and returns back to the valve through the system return port 9d, in the 0% boiler water valve position no boiler water is mixed with the water in the radiation system. In positions between 0 and 100% a regulated amount of boiler water mixes with the water moving through the radiation, allowing control of the water temperature going to the radiation between the ambient temperature of the radiation and the boiler water temperature. Both of these systems have what is referred to as a primary and secondary loop, with high temperature water flowing through the primary loop (the boiler loop) and lower temperature water flowing through the secondary loop (the radiation). Another method as shown in FIG. 4 utilizes an additional pump 14 that is controlled at varying speeds to move water from the primary loop 13 to the secondary loop 15, as the pump speed 14 is increased the temperature of the secondary loop can be increased. This system has more complex components than the 3 and 4 way valve systems described above, greater care in piping practices must be used in order to eliminate unwanted flow of heat do to conductive flow, and can not be manually controlled as three and four way valves may be.
The above-described prior art systems, when using both primary and secondary loops require mixing valves which are rather expensive, can be complicated and require power assist such as motors to effect the appropriate operation of the three or four way mixing valve.
An object of this invention is to provide a hydronic heating/cooling system with primary and secondary systems in which the transfer of the heat medium between the primary and secondary systems is accomplished, simply, economically and without the need of additional energy input, such as to a motor.
Another object of this invention is to provide such a system which eliminates using three and four way mixing valves.
Yet another object of this invention is to provide such a system which is easy to repair, comprises simple and well-known components and effectively achieves the desired transfer with minimum complexity and cost.
Other objects and advantages and features of this invention become more apparent from the following description.